1. Field of the Invention
This invention relates to camera systems having a finder system of the external type provided independently of a photographic system and, more particularly, to camera systems having a finder system of the external type having a magnification varying means which is operatively associated with a magnification varying means of the photographic system of a photographic camera or a video camera, wherein a lens group constituting part of the finder system is made to move in unison with a lens group constituting part of the photographic system, thereby achieving simplification of the lens barrel.
2. Description of the Related Art
In the finder system arranged in independent relation to the photographic system as in the so-called lens shutter camera, or the external type finder system, it has been the common practice that when the photographic system has a zooming means, the finder system, too, is provided with a magnification varying means which is operatively associated With the zooming means of the photographic system.
By this, the image to be photographed within a frame on the photosensitive surface is made to coincide with the object image observed in the field of view of the finder.
There have been many previous proposals for using the magnification varying means in the finder system and carrying out variation of the magnification of the finder image in automatic response to zooming of the photographic system, or for such a magnification variable finder of the external type.
In general, the camera system that affords the finder system of the external type having the magnification varying means is relatively easy to facilitate minimization of the size of the photographic system. To drive the operating mechanism for the finder system in predetermined coordination with the zoom control mechanism of the photographic system, however, a problem arises that the operating mechanism becomes very complicated in structure.
Particularly when the zoom ratio is increased, the complexity of the control mechanism for coordinating the finder system with the photographic system tends to increase.
By the way, Japanese Laid-Open Patent Application No. Sho 62-209425 has proposed a technique wherein the photographic lens and the magnification variable finder optical system have a common cam frame made with camming slots for the photographic lens cut therein to form a locus of motion of the photographic lens and with camming slots cut therein to form a locus of motion of the finder optical system, or to be solely used for the finder.
However, to allow the provision of both types of camming slots for the photographic lens and the finder optical system to be made, all the camming slots must be designed so as not to cross one another. In addition, on manufacturing it, a few problems will arise.